Is more complicated than that. If those chemicals are lipophilic substances (attracted by fat) then cows should accumulate more. But if they are hydrophilic substances, attracted by water, we need to remember that lettuce is 96% water. One Kg of meat is rich energy food and not equivalent to Kg of lettuce. We would need to eat much more Kg of lettuce for the same.
As we are talking about chocolate pie I assume that they are lipohilic. But vegetables aren't an homogeneous group and some seeds and fruits have a lot of oil. We could find that meat is safer than some of them and expect a much higher variability inside the group than with meat.
I assume this, but I don't know every chemical in this group. What is strange is that Kale does not seem like a very oily plant (in my opinion, could be wrong). This species store sugars as chill protection.
The main question to ask here is if this chemicals are causing chronic inflammation and in that case if is related with the obesity epidemic. We know that people living in the upper course of the rivers and allegedly drink better quality water are less obese on average.
A possible null hypothese to start could be: A body accumulating toxic substances in the fat cells, could react making more fat cells as a defense (to dilute the poison by cell)?.
Are somebody checking if the areas with more chemicals in the water show a higher average of Body Mass Index?
As we are talking about chocolate pie I assume that they are lipohilic. But vegetables aren't an homogeneous group and some seeds and fruits have a lot of oil. We could find that meat is safer than some of them and expect a much higher variability inside the group than with meat.